How can medication be correctly given to a rat? - briefly
Use a calibrated syringe to deliver the appropriate dose, calculated per kilogram of body weight, via oral gavage, subcutaneous, or intraperitoneal injection while maintaining aseptic technique. Confirm correct placement, observe the rat for immediate reactions, and document the administration details.
How can medication be correctly given to a rat? - in detail
Administering drugs to a laboratory rat requires precise planning, proper equipment, and adherence to ethical standards.
First, determine the appropriate route based on the drug’s properties, required absorption rate, and experimental goals. Common routes include oral gavage, intraperitoneal (IP) injection, subcutaneous (SC) injection, and intravenous (IV) injection.
Dose calculation
- Convert the desired dose (mg kg⁻¹) to the animal’s weight (g).
- Multiply the dose by the rat’s mass (kg) to obtain the total amount of drug.
- Adjust for drug concentration in the formulation to derive the injection or gavage volume.
- Keep the final volume ≤ 0.2 mL kg⁻¹ for IP and SC injections, and ≤ 0.1 mL kg⁻¹ for IV administration.
Preparation
- Dissolve or suspend the compound in a sterile, physiologically compatible vehicle (e.g., saline, phosphate‑buffered saline, or appropriate oil).
- Filter sterilize if the solution is injectable.
- Label the syringe with drug name, concentration, and administration time.
Animal handling
- Restrain the rat using a calm, firm grip or a restraining device to minimize stress.
- Verify that the animal is healthy, with no signs of distress or injury.
Oral gavage
- Use a flexible gavage needle sized for the rat’s body weight (e.g., 1–1.5 mm outer diameter).
- Insert the needle gently along the midline of the tongue, advancing until the esophagus is reached, avoiding the trachea.
- Deliver the calculated volume slowly, then withdraw the needle and observe the rat for regurgitation.
Intraperitoneal injection
- Locate the lower right quadrant of the abdomen, avoiding the midline and the bladder.
- Insert a 25‑27 G needle at a shallow angle (30–45°) to the skin, penetrating the peritoneal cavity.
- Inject the dose steadily, then withdraw the needle and apply gentle pressure to the puncture site.
Subcutaneous injection
- Pinch a fold of loose skin on the dorsal neck or scruff.
- Insert a 25‑27 G needle bevel up at a 45° angle into the subcutaneous space.
- Depress the plunger slowly, withdraw the needle, and release the skin fold.
Intravenous injection
- Preferred sites are the lateral tail vein or the femoral vein.
- Warm the tail to dilate vessels, then use a 27‑30 G catheter or needle.
- Confirm venous entry by a flash of blood, then inject the drug over 5–10 seconds.
Post‑administration monitoring
- Observe the rat for at least 15 minutes for signs of distress, respiratory difficulty, or abnormal behavior.
- Record the exact time, dose, route, and any adverse reactions in the animal log.
Safety and compliance
- Wear appropriate personal protective equipment (gloves, lab coat, eye protection).
- Follow institutional animal care guidelines and obtain required approvals before any dosing procedure.
By following these steps, researchers can ensure accurate, reproducible drug delivery to rats while maintaining animal welfare and experimental integrity.